Based on a recent review and a contribution for the 20 years anniversary edition of the scientific journal Public Understanding of Science, reflections are made about the last twenty years of achievements and failures in the theory, practice and policy of Public Engagement with Science (PES). The ‘deficit theory’ which still today characterize many scientific activities that address citizen can be criticized for ‘one-way communication’, ‘sanctity of expertise’, and treatment of the publics as ‘homogeneous’. When arguing for the need for public engagement with science it is question about not problematising ‘the public’, taking values seriously and instead educating ‘the experts’, and recognising both the ‘legitimacy of wider concerns’ and the ‘democratic imperative’. Public Engagement with Science as strategy is building upon a normative commitment to the idea of democratic science policy, and it is argued that public engagement can be a part of this. It could not have been anticipated in the early and even mid 1990s the extent to which ‘engagement talk’ would take root in a UK but also more widely European context, with many examples at a larger international level to back this up. However, maybe public engagement has too often become a procedural response in research and innovation projects to a more fundamental political challenge. The challenge of scientific governance or democratisation dwarfs the small processes of engagement that are put in place. Likewise, the mini-publics brought together for dialogue exercises look microscopic against the backdrop of global science and its governance. Maybe it has been over-promised what such public engagement exercises can deliver. We can safely conclude that, despite all the ‘from deficit to democracy’ talk, no such easy shift has been made. At best, partial progress can be claimed. We must be aware about the sometimes-enormous gap between the easy rhetoric of engagement and institutional practice, and to the disjunctures, erroneous assumptions and tensions in the very definition of ‘public engagement with science’. The existence of both scientific indifference to social science and of real asymmetries of disciplinary power between science and social science cannot either be denied. Moreover there seems to be a tendency to dump all the difficult socio-institutional challenges into the ‘social science’ basket – thus liberating scientific institutions from their own obligation to take such matters seriously. Maybe there is a need to ‘bring the political back in when talking about Public Engagement with Science but this would require a reconceptualisation of ‘the political’. Other authors have suggested how the field might be reconceptualised in terms of the public representation of science (Jasanoff), ‘public interpretations of science and technology’ (Wynne), and a focus on political imaginaries and ‘necessary fictions’ (Nowotny).